Open-hearth furnace.



No. 869,617. PATENTED 00129. 190?. T. s. BLAIR, JB.-

OPEN HEARTH FURNACE.

APPLIOATION FILED JULY 6,.1907.

numdpp q/vi ubman UNITED' STA' I ES PATENT OFFICE.-

THOMAS S. BLAIR, .lR., OF ELMIIURST, ILLINOIS.

OIPEN-HEARTH FURNACE.

T all whom it may concern:

Be it known that l, TrioMAs' S. BLAIR, Jr., a citizen of the United States, residing at Elmhurst, in the county of Dupage and State of Illinois, have invented certain new and useful Improvements in Open-Hearth Furnaces, of which the following is a specification.

- My invention relates to certain new and useful improvements in open hearth furnaces, and the object of my invention is to so improve the construction and the method of operating the furnace as, to enable me to build furnaces of any desired length, and to operate the same with greater rapidity and economy of fuel than has heretofore been possible.

In the prior construction of furnaces, it has been found, as a matter of fact, that it was impossible to carry the combustion over a length of hearth greater than 30m 32 feet, and consequently this has been universally adopted as the maximum length of hearth which could be practically used.

I have discovered that it is possible to increase the length of the hearth to any desired extent and that the combustion of the gases can be carried over the hearth from end to end of the furnace, even when the hearth is 75 feet or more in length. Broadly speaking, my discovery is that, by feeding over the gases of combustion a blanket of air which is in excess of the maximum amount of air necessary for combustion, the gases .will be held in close contact with the bath for the entire length of the furnace, and that the combustion will be carried to the full length thereof.

In the building of open hearth furnaces it has heretofore been customary .to design the air ports on the theory that it was only necessary to have them of a size which would merely provide sufficient air for the combustion of the gases. By my invention 1 provide air ports of such size that they will supply anamount of air in excessof the amount required for combustion,

which excess is'preferably approximately equal to the amount necessary for combustion.

I have also discovered that, by feeding the gases into .the furnace in acomparatively thin stream, and feeding the air over the top of the gases in a comparatively thin stream, a larger perce'ntageof the heat generated by the combustion is delivered to the bath and the cost for fuel correspondingly reduced per ton of product.

I have also discovered that in order to provide a space for the increased amount of air fed into the fur- Specification of Letters Patent.

Application filed July 6, 1907- Ssrial No. 882.487.

Patented Oct. 29, 1907.

space between the top of the bath and the roof the l have also discovered that by having the roof of the furnace flat for the entire length of the hearth, the products of combustion will be held down in a more effective manner on the bath.

Referring to the drawings wherein I show an openhearth furnace embodying my invention and discovery, and wherein the same part is designated by thesanie reference numeral wherever it occurs, Figure 1 is a central longitudinal section; and Fig. 2 is a section taken on line 2, 2 of Fig. l.

l designates the hearth supported on the usual substructure 2, and 3 designates the side walls provided with the usual charging doors 4.

'5 designates the roof which is shown as flat with the upwardly extending endsections 6, below which are located the air ports 7-, one in each end of the furnace.

Upon reference to Fig. v.2 it will be seen that each of the air ports 7 extends the full wid th of the furnaceand are adapted to supply a volume of air in excess of that required for the maximum combustion.

8 designates the usual down-take ports for the air, which of course are also of correspondingly increased size, inorder to correspond to the increased size of the air ports 7.

. 9, 9 designate a pair of gas ports, which are arranged in line with each other, one pair in each end of the furnace and located immediately bclowthe air ports 7. it

will be noticed that these gas ports are of a width in excess of their height, so that the gases are delivered into' the furnace in a comparatively shallow stream immediately below the air supply through the air ports 7. The gases beneath the blanket of air supplied through air ports 7 spread out in the space between the lower strata of air andthe top of the bath and are confined therein. The air necessary for the combustion of the gases is drawn from the air between the gases and the gases in passing through the furnace are never released from the confining effect of the air between the gases and the roof. As the gases of combustion are fed in a comparatively thin strcamintothc furnace and are held in this condition and down on the bath by the blanket of air, it will be readily seen that a larger percentage of the heat developed will be utilized for heating the bath than has heretofore been possible with a resulting economy both in theiucl and the longer .liie of the furnace.

lOO

"the fut-mete.

In an open he gas port udepteti-to as to insure a surplus of air remaining over the gases of 'c om'bus ion when hey pass out of theiuinace'. 1

Having thus described my invention What I' claim as new and desire to secure by'LetterePatent is:

1. The method of-lieating open hearth furnaces which consists in supplying between the'roof-ot the furnace and the burning gases a volume of :iir in excess of tl'ie amount necessary-forv complete combustion'whereby there will always be a. stretum of air interposed between the burn-- ing gases and thereof of the furnace.

2. The methogl of heating open hearth furnaces which consists in supplying the gases of combustion tothe tun time in e. stream of greater width than thickn'ess,- supply-,-

ing a volume of air in excess of the amount necessary for complete combustion between the, gases and theroof and Q over the entlre 's't'rearn 'ci the gases whereby the gases of combustion will he held. in a thin stream against the bath by' the volume of, air between the gases and the-root of fnrhecethe combinationwith a 91 a streanrof gas into the fur- :1 ot er the gas'porteml adapted etiveen the gas and the roof ofmice of an 2111' port 1 to deliver .1 streum oi the .furnaee, the gas can hit" ports being so proportioned in r'ei-atio to each ether that the supply-0f air will ll be noted that by. providing a' large arnount of space betweenv the hearth and theroof there will'always be sucha volume of air between'the gasesand the roof deliver a stream'of gas into the furnace, of an air port Q v {mew- ,lo ztted' over thegas port anti'adepted to deliver afstreem of ii -between the gas and then-00f ofrthe furnace; the gas and air ports being so proportioned in relation to each other that the supply of {iir will always be in excess.

of. that required for thecfomplete combustion of the gas 7 whereby there will alwnys be it stratum of air between the gas ami the roof to hold th'e gas in intimatecontact *wi'thfl the bath and'awa y' from the r'oof.

In an open hearth furnace the conibination with a pair of-ges ports arranged side by side and adapted-to extending eve: the pair of gas ports and adapted to deliver 8. strettm oiair between the gas andthe roof, the gas and airports being so proportioned in relation to Jean-h other the. the supply of air will'always be in excess of that'require 'for the complete combustion of the gases,

the surplus air operating to hold the gases against the bath for the length ofthe furnace. t

In testimony whereof I'eflix my signature in presence of two'wit esses. 1 t

V THOMAS s. nL mQJn, :L. s.] I

' Witziesses: v

C. B. MOLAMPHY, 

